Collagenous colitis: a case series with confocal laser microscopy and histology correlation.

Confocal laser endomicroscopy (CLE) was carried out in seven patients with chronic watery diarrhea (three men; age range 68 - 84 years) to find the correspondence between CLE and histological findings in collagenous colitis. On the basis of the CLE images, two to five biopsies were performed in various segments of the colon. The endoscopic and histological diagnoses of collagenous colitis were made blindly. The quality of the CLE images was quantified from 0 (the endoscopist could not visualize the corresponding histologic equivalent) to 3 (the endoscopist could identify >or= 80 % of the corresponding histologic equivalent). Four out of seven patients had histological findings of collagenous colitis. Correspondence between histology and CLE images yielded the following scores: 3 for epithelial architecture, 3 for goblet cells, 3 for vessels, and 2 for inflammatory infiltrate. In collagenous colitis patients, CLE identified a well-defined "shell" around the crypts, corresponding to the increase in the thickness of the subepithelial collagenous plate evidenced by histology. CLE appears to be a promising means of identifying typical collagenous colitis features.